noise

Matlab filter electical spikes in accelerometric data

好久不见. 提交于 2019-11-28 12:40:51
问题 I have a dataset of accelerometric data that is affected by electical spikes. I'm looking for a good method to filter out or reduce these spikes as need to calculate on these data a rolling window of FFT and other statistical indicators such as kurtosis and skewness. I can't simply delete these outliers or replace them with NaN. Sampling 2000[hz] Until now I've tried on MATLAB 2012b: Wavelet denoising (Haar wavelet) Median Filter Despike and iterpolate approach Can you suggest a proper

Simulating TV noise

拟墨画扇 提交于 2019-11-28 03:36:10
I have googled a bit but was never able to find an answer. What should be my first approach to simulate a video and audio noise from TV on screen? I mean, when my TV antenna is removed but the TV is still on (like they show in Japanese horror movies sometimes). I can use ffmpeg or any other technique but what is the simplest possible form of the signal? Create video and audio noise, artifacts, and errors with ffmpeg Noise Using filters The geq (video "generic equation") filter (with nullsrc as its "blank canvas") can create video noise, and the aevalsrc filter can create white noise audio:

Reducing wiimote pitch/roll variations

两盒软妹~` 提交于 2019-11-28 02:20:28
I want to use the wiimote to control a cursor WITHOUT the infrared sensor bar. I'm using the pitch and roll values for this. The problem is that when the pitch is close to 0 degrees, the roll is very unstable, and when the pitch is close to 90 degrees, it is itself very unstable, but the roll is fine. Im polling the wiimote very frequently, so im averaging the last 20 values for both pitch and roll, and I can get the cursor to go where I want. The only problem is that there is still alot of uncontrolable shaking. Any ideas on how I can reduce it? (Or even get a more precise position without

Fastest Perlin-Like 3D noise algorithm?

假如想象 提交于 2019-11-27 23:15:28
问题 It's been well over 20 years since Ken Perlin first invented his noise. Has anybody managed to make a faster kind of 3D noise generator with properties close to Perlin's (procedural, natural-looking grouping, reduced banding, regular feature size, etc)? I'm trying to build a procedural world generator but currently Perlin just isn't cutting it. I admit my implementation isn't the best it could be right now, but if I'm about to rewrite it anyway I wondered if there was a better algorithm

Determine frequency from signal data in MATLAB

六月ゝ 毕业季﹏ 提交于 2019-11-27 19:51:22
I have data from a sensor and I need to find the frequency of it. It looks like fft() seems to be the way to go, but the MATLAB docs only show how to get a graph of the frequencies, I don't know what to do from there. Here's what my data looks like: One way to go is indeed to use an fft. Since the fft gives you the frequency representation of the signal, you want to look for the maximum, and since the fft is a complex signal, you will want to take the absolute value first. The index will correspond to the normalized frequency with maximum energy. Last, if your signal has an offset, as is the

How to use Kalman filter in Python for location data?

旧城冷巷雨未停 提交于 2019-11-27 17:21:21
[EDIT] The answer by @Claudio gives me a really good tip on how to filter out outliers. I do want to start using a Kalman filter on my data though. So I changed the example data below so that it has subtle variation noise which are not so extreme (which I see a lot as well). If anybody else could give me some direction on how to use PyKalman on my data that would be great. [/EDIT] For a robotics project I'm trying to track a kite in the air with a camera. I'm programming in Python and I pasted some noisy location results below (every item also has a datetime object included, but I left them

Matlab filter electical spikes in accelerometric data

浪子不回头ぞ 提交于 2019-11-27 15:23:29
I have a dataset of accelerometric data that is affected by electical spikes. I'm looking for a good method to filter out or reduce these spikes as need to calculate on these data a rolling window of FFT and other statistical indicators such as kurtosis and skewness. I can't simply delete these outliers or replace them with NaN. Sampling 2000[hz] Until now I've tried on MATLAB 2012b: Wavelet denoising (Haar wavelet) Median Filter Despike and iterpolate approach Can you suggest a proper approach to deal with these data? Download example dataset I would suggest some local smoothing. By defining

Reducing noise on Data

 ̄綄美尐妖づ 提交于 2019-11-27 12:34:56
问题 I have 2 lists with data points in them. x = ["bunch of data points"] y = ["bunch of data points"] I've generated a graph using matplotlib in python import matplotlib.pyplot as plt plt.plot(x, y, linewidth=2, linestyle="-", c="b") plt.show() plt.close() Would I be able to reduce the noise on the data? Would a Kalman filter work here? 回答1: It depends how you define the "noise" and how it is caused. Since you didn't provide much information about your case, I'll take your question as "how to

Using imnoise to add gaussian noise to an image

对着背影说爱祢 提交于 2019-11-27 12:33:46
问题 How do I add white Gaussian noise with SNR=5dB to an image using imnoise ? I know that the syntax is: J = imnoise(I,type,parameters) and: SNR = 10log 10 [var(image)/var(error image)] How do I use this SNR value to add noise to the image? 回答1: Let's start by seeing how the SNR relates to the noise. Your error image is the difference between the original image and the noisy image, meaning that the error image is the noise itself. Therefore, the SNR is actually: SNR = 10log 10 [var(image)/var

Noise Estimation / Noise Measurement in Image

邮差的信 提交于 2019-11-27 11:20:10
问题 I want to estimate the noise in an image. Let's assume the model of an Image + White Noise. Now I want to estimate the Noise Variance. My method is to calculate the Local Variance (3*3 up to 21*21 Blocks) of the image and then find areas where the Local Variance is fairly constant (By calculating the Local Variance of the Local Variance Matrix). I assume those areas are "Flat" hence the Variance is almost "Pure" noise. Yet I don't get constant results. Is there a better way? Thanks. P.S. I